Compressor

ABSTRACT

A swash plate compressor ( 41 ) is disclosed, wherein a shaft ( 43 ) is divided into a rear shaft ( 45 ) and a front shaft ( 47 ) coupled to each other through a torque limiter ( 65 ) with center holes ( 51, 69 ) communicating with each other. A lug plate ( 25 ) is fixed to the rear shaft ( 45 ). Machining of the center holes is thus facilitated while at the same time eliminating the need for rust-proofing of the torque limiter.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a compressor having a torque limiter for interrupting a power transmission under an excessively large load.

2. Description of the Related Art

A compressor having a torque limiter is shown in FIG. 6. In a swash plate compressor 11, a drive shaft 19 is journaled between a front housing 15 and a cylinder block 17 defining a control pressure chamber 13, and a pulley 23 is mounted at the forward end portion of the drive shaft 19 through a torque limiter 21. A discal lug plate 25 is fixed to the portion of the drive shaft 19 in the control pressure chamber 13, and a swash plate 27 is arranged in engagement with the lug plate 25. A plurality of pistons 29 are slidably arranged along the outer periphery of the swash plate 27. In this swash plate compressor 11, the rotation of the pulley 23 rotates the drive shaft 19 and the lug plate 25 fixed to the drive shaft 19 through the torque limiter 21. With the rotation of the lug plate 25, the swash plate 27 engaged thereby is rotated. The rotation of the swash plate 27 drives the pistons 29 thereby discharging a fluid.

In this swash plate compressor 11, a lip seal 31 is arranged between the drive shaft 19 and the front housing 15 to prevent leakage of a refrigerant or the like from inside the control pressure chamber 13. In order to supply a lubricating oil to the lip seal 31, a very long center hole 33 is formed from the rear end of the drive shaft 19 to the neighborhood of the lip seal 31.

However, this long center hole 33, is difficult to form due to the liability of the cutter blade to break or the hole to be curved on the one hand and a long period of time required by the drilling process on the other hand, thereby posing the problem of high cost.

The torque limiter 21 is intended to break a thin portion with an increased axial force by retightening the screw under an excessively large torque. With the secular change of the friction coefficient, the torque limiter 21 cannot be operated with an expected torque. In order to stabilize the friction coefficient, therefore, a rust-proofing process is executed by applying grease or otherwise to the screw surface and seat surface. Also, the torque limiter 21, which is mounted outside the compressor, may be exposed to water, which requires rust-proofing. Further, in order to prevent the screw portion from being flooded with water, a rubber cap 35 is required. All these requirements pose the problem of increased cost.

Other examples of the swash plate compressor are described in Japanese Unexamined Patent Publications. Nos. 2003-307265 and 2003-206950.

SUMMARY OF THE INVENTION

The object of this invention is to solve these problems and provide a compressor which facilitates the machining of the center hole and eliminates the need of rust-proofing the torque limiter.

In order to achieve this object, according to a first aspect of the invention, there is provided a compressor comprising a shaft (43) passed through the front wall portion of a housing (15), a lip seal (31) arranged on the portion of the shaft (43) passing through the front wall portion, a rotary member (25) arranged on the shaft (43) in the housing (15), compression mechanisms (27, 29) rotated by the rotary member (25), and lubricating oil feeding paths (51, 69) leading from the rear portion of the housing (15) to the lip seal (31) through the shaft (43), wherein the shaft (43) has a front shaft (47) and a rear shaft (45) coupled to each other through a torque limiter (65) with lubricating oil feeding paths (51, 69) in communication with each other, and the rotary member (25) fixed to the rear shaft (45).

According to a second aspect of the invention, there is provided a compressor, wherein the rotary member is a lug plate, and the compression mechanisms are pistons (29) and a swash plate (27) rotated by the lug plate (25).

In these aspects of the invention, the length of the hole formed in the shaft (45, 47) can be shortened, and the process of forming the center hole is facilitated. Also, by using a tubular material for the rear shaft (45), costs can be remarkably reduced. Further, the interposition of the torque limiter (65) between the rear center hole (51) and the front center hole (69) makes it possible to immerse the female screw (53) and the male screw (63) of the torque limiter (65) in the lubricating oil of the refrigerant, thereby eliminating the need for rust-proofing. Also, the torque limiter (65), which is located in the housing (15), is not exposed to water, thereby eliminating the need of a waterproof cap or rust-proofing.

According to a third aspect of the invention, there is provided a compressor, wherein the torque limiter (65) includes a male screw portion (63) formed on the end surface (59) of one of the front shaft (47) and the rear shaft (45) through a small-diameter portion (61) and a female screw portion (53) formed inward of the other one of the front shaft (47) and the rear shaft (45) from the end surface of the other shaft, and wherein the male screw portion (63) and the female screw portion (53) are screwed to each other while the end surface of the one shaft and the end surface of the other shaft are in contact with each other. Thus, the torque limiter can be configured with a simple structure and the cost can be reduced.

According to a fourth aspect of the invention, there is provided a compressor, wherein the one shaft having the male screw portion (63) is the front shaft (47) and the other shaft having the female screw portion (53) is the rear shaft (45). By using a tubular member for the rear shaft (45), the female screw portion (53) can be easily machined.

According to a fifth aspect of the invention, there is provided a compressor, wherein the front and rear parts of the rear shaft (85) are journaled by bearings (73, 57). Even in the case where the screw portion or the seat surface is not precise, decentering is prevented.

According to a sixth aspect of the invention, there is provided a compressor, wherein the front shaft (47) includes a large-diameter portion (75) for preventing the torque limiter (65) from coming off from the front wall of the housing (15) in the case where the torque limiter (65) is activated and separated from the rear shaft (45).

According to a seventh aspect of the invention, there is provided a compressor comprising a shaft (43) having one end portion (77) connected to a power source and the other end portion reaching the interior of a housing (15) through the wall portion of the housing (15), a rotary member (25) arranged on the shaft (43) in the housing (15), and compression mechanisms (27, 29) rotated by the rotary member (25), wherein a torque limiter (65) is arranged on that part of the power transmission path leading from the one end portion (77) of the shaft (43) to the rotary member (25) which is located inside the housing (15).

According to a eighth aspect of the invention, there is provided a compressor, wherein the rotary member is a lug plate (25) and the compression mechanisms (27, 29) are a swash plate (27) and pistons (29) rotated by the lug plate (25). In these configurations, the torque limiter (65) which is located in the front housing (15) is not exposed to moisture, thereby eliminating the need of a waterproof cap and rust-proofing. Also, the torque limiter, being arranged in the housing, is lubricated by the lubricating oil of refrigerant so that a stable working torque can be maintained for a long period of time.

The reference numerals in the parentheses attached to the respective means represent an example of correspondence with specific means described in the embodiments later.

The present invention may be more fully understood from the description of preferred embodiments of the invention, as set forth below, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view showing a swash plate compressor according to a first embodiment of the invention.

FIG. 2 is a sectional view showing the essential parts of the swash plate compressor of FIG. 1.

FIG. 3 is a sectional view showing the essential parts of the swash plate compressor of FIG. 1 with power interrupted.

FIG. 4 is a longitudinal sectional view showing the circulation of the refrigerator oil in the swash plate compressor shown in FIG. 1.

FIG. 5 is a longitudinal sectional view showing a swash plate compressor according to a second embodiment of the invention.

FIG. 6 is a longitudinal sectional view showing the swash plate compressor as related art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The Embodiments of the invention will be explained below with reference to FIGS. 1 to 5. In these embodiments, the same component parts as those of the compressor shown in FIG. 6 are designated by the same reference numerals, respectively, and are not described.

A swash plate compressor 41 according to a first embodiment of the invention is shown in FIGS. 1 to 4. In this swash plate compressor 41, a drive shaft 43 has a rear shaft 45 and a front shaft 47.

The rear shaft 45 is preferably machined from a tubular material and formed with a rear center hole 51 from the front end surface 49 to the rear end portion thereof along the axial direction. This rear center hole 51 is for sending forward the lubricating oil of the refrigerant from a high-pressure oil storage container (not shown) arranged in the rear of the compressor. The front end portion of the rear center hole 51 of the rear shaft 45 is formed with a female screw portion 53. Also, a bearing surface 55 is formed on the outer periphery of the rear end portion of the rear shaft 45. A bearing 57 is interposed between the bearing surface 55 and a cylinder block 17 to journal the rear end portion of the rear shaft 45. A lug plate 25 is fitted under pressure on the outer periphery of the front end portion of the rear shaft 45.

The front shaft 47, on the other hand, has a male screw portion 63 protruded rearward from the rear end surface 59 through a small-diameter portion 61. This male screw portion 63 is screwed with the female screw portion 53 of the rear shaft 45 by bringing the rear end surface 59 of the front shaft 47 into contact with the front end surface 49 of the rear shaft 45. The front end surface 49 and the female screw portion 53 of the rear shaft 45 and the rear end surface 59, the small-diameter portion 61 and the male screw portion 63 of the front shaft 47 make up a torque limiter 65.

The front shaft 47 is formed with a front center hole 69 forwardly leading from the rear end surface 59 to the oil feeding opening 67 formed in the neighborhood of the lip seal 31. This front center hole 69 is for supplying lubricating oil of the refrigerant from the rear center hole 51 to the lip seal 31.

A bearing surface 71 is formed on the rear side of the oil feeding opening 67 of the front shaft 47, and a bearing 73 is interposed between the bearing surface 71 and the front housing 15 thereby to journal the rear portion of the front shaft 47. A flange portion 75 is protruded radially outward from the rear end of the front shaft 47. In the case where the torque limiter 65 is operated and the small-diameter portion 61 is broken, the flange portion 75 engages the outer periphery of the bearing 73 of the front housing 15 and thus prevents the front shaft 47 from coming off.

A pulley mount 77 having a male screw is arranged at the front end portion of the front shaft 47, and a pulley (not shown) is adapted to be mounted on the pulley mount 77.

With this configuration, as long as the compressor is operated under normal conditions and a normal load is imposed on the lug plate 25 from the pulley mount 77, the rear end surface 59 of the front shaft 47 presses the front end surface 49 of the rear shaft 45 due to the screwed relation between the female screw portion 53 and the male screw portion 63 of the torque limiter 65 so that the power is transmitted from the front shaft 47 to the rear shaft 45. Then, the drive force is transmitted from the lug plate 25 fixedly fitted under pressure in the rear shaft 45 to the piston 29 through the swash plate 27.

Also, as long as the compressor is operating normally, as shown in FIG. 4, lubricating oil of the refrigerant flows from the high-pressure oil storage (not shown) to the oil feeding opening 67 through the rear center hole 51 in the rear shaft 45 and the front center hole 69 of the front shaft 47 and is supplied to the lip seal 31.

In the process, lubricating oil of the refrigerator is also supplied to the female screw portion 53 and the male screw portion 63 of the torque limiter 65. As a result, corrosion can be prevented without rust-proofing and the friction coefficient is stabilized to prevent the secular variation of the working torque.

In the case where the piston is locked or otherwise an excessively large load is imposed between the front shaft 47 and the lug plate 25, the front shaft 47 is rotated with respect to the rear shaft 45, and the male screw portion 63 is pulled with a strong force from the front shaft 47 due to the screwed relation between the male screw portion 63 of the front shaft 47 and the female screw portion 53 of the rear shaft 45, resulting in the breakage of the small-diameter portion 61. Consequently, power transmission is interrupted between the rear end surface 59 of the front shaft 47 and the front end surface 49 of the rear shaft 45.

As described above, the swash plate compressor 41 includes the shaft 43 extending to the cylinder block 17 through the front housing 15, the lip seal 31 arranged on the portion of the shaft 43 passed through the front housing 15, the lug plate 25 arranged on the shaft 43 in the front housing 15, and the center holes 51, 69 leading from the rear portion of the shaft 43 to the lip seal 31 through the shaft 43, wherein the shaft 43 has the rear shaft 45 and the front shaft 47 coupled to each other through a torque limiter with the center holes 51, 69 communicating with each other, while the lug plate 25 is fixed on the rear shaft 45. As a result, the center holes to be bored can be shortened, thereby facilitating the machining of the center holes. Especially, since tubular material is used for the rear shaft 45, cost is reduced remarkably. Also, the interposition of the torque limiter 65 between the rear center hole 51 and the front center hole 69 makes it possible to immerse the female screw portion 53 and the male screw portion 63 of the torque limiter 65 in lubricating oil of the refrigerant. Therefore, rust-proofing can be eliminated, and a stable working torque can be maintained for a long period of time. Also, the torque limiter 65, being located within the front housing 15, is not exposed to water, and as a result, the waterproof cap and rust-proofing are not required for reduced cost and stable working torque.

Also, the torque limiter 65 has the male screw portion 63 through the small-diameter portion 61 on the rear end surface 59 of the front shaft 47, the female screw portion 53 is formed inward of the front end surface 49 of the rear shaft 45, and the male screw portion 63 and the female screw portion 53 are screwed to each other while the rear end surface 59 of the front shaft 47 and the front end surface 49 of the rear shaft 45 are in contact with each other. Therefore, the torque limiter 65 can be configured with a simple structure for reduced cost.

Further, the rear end portion of the front shaft 47 is formed with the flange unit 75 protruded radially outward. Even in the case where the torque limiter 65 is activated and the small-diameter portion 61 is broken, the front shaft 47 is prevented from coming off.

Next, a second embodiment will be explained with reference to FIG. 5.

Also in this swash plate compressor 81, a drive shaft 83 has a rear shaft 85 and a front shaft 87. However, unlike in the first embodiment shown in FIG. 1, the rear shaft 85 is extended to a point forward of the front end of the bearing 73 and rearward of the oil feeding opening 67, and a bearing surface 89 is formed on the outer periphery of the extension of the rear shaft 85. Thus, the rear shaft 85 is correspondingly longer and has the ends thereof journaled by the bearings 73 and 57. Also, the lug plate 25 is fitted under pressure on the outer periphery of the rear shaft 85 at a point a predetermined distance rearward of the forward end surface thereof. The front shaft 87, on the other hand, is correspondingly shortened by the additional length of the rear shaft 85, and not journaled directly by a bearing, but is supported on the rear shaft 85 by the screwed relationship between the female screw portion 53 and the male screw portion 63 of the torque limiter 65.

As described above, in this swash plate compressor 81, the front and rear end portions of the rear shaft 85 are journaled by the bearings 57, 73, and therefore, decentering is prevented even in the case where the screwed portions or the seat surface is not precise.

Although the aforementioned embodiments refer to a compressor with the swash plate engaged by the pistons through the shoes, the invention is not limited to this configuration, and can of course be also used with a swing-type swash plate compressor for driving the pistons with a combination of the drive plate and the wobble plate.

While the invention has been described by reference to specific embodiments chosen for purposes of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the basic concept and scope of the invention. 

1. A compressor comprising: a shaft passed through a front wall portion of a housing; a lip seal arranged on the portion of the shaft passing through the front wall portion; a rotary member arranged on the shaft in the housing; compression mechanisms rotated by the rotary member; and lubricating oil feeding paths leading from a rear portion of the housing to the lip seal through the shaft; wherein the shaft has a front shaft and a rear shaft coupled to each other through a torque limiter with the lubricating oil feeding paths communicating with each other, and the rotary member fixed on the rear shaft.
 2. The compressor according to claim 1, wherein the rotary member is a lug plate, and the compression mechanisms are pistons and a swash plate rotated by the lug plate.
 3. The compressor according to claim 2, wherein the torque limiter includes a male screw portion formed on the end surface of one of the front shaft and the rear shaft through a small-diameter portion and a female screw portion formed inward of the other one of the front shaft and the rear shaft from the end surface of the other shaft, and wherein the male screw portion and the female screw portion are screwed to each other while the end surface of the one shaft and the end surface of the other shaft are in contact with each other.
 4. The compressor according to claim 3, wherein the one shaft having the male screw portion is the front shaft and the other shaft having the female screw portion is the rear shaft.
 5. The compressor according to claim 2, wherein the front and rear parts of the rear shaft are journaled by bearings.
 6. The compressor according to claim 2, wherein the front shaft includes a large-diameter portion for preventing the torque limiter from coming off from the front wall of the housing in the case where the torque limiter is activated and separated from the rear shaft.
 7. A compressor comprising: a shaft having a one end portion passed through the wall portion of a housing connected to a power source and the other end portion reaching the interior of the housing; a rotary member arranged on the shaft in the housing; and compression mechanisms rotated by the rotary member; wherein a torque limiter is arranged on that part of the power transmission path leading from the one end portion of the shaft to the rotary member which is located inside the housing.
 8. The compressor according to claim 7, wherein the rotary member is a lug plate and the compression mechanisms are the pistons and the swash plate rotated by the lug plate. 